Support count=0 to retrieve totalResults only

Change-Id: Ibc64fca72d2e8464992fb05dd23507a099be1349
diff --git a/src/main/java/de/ids_mannheim/korap/response/Result.java b/src/main/java/de/ids_mannheim/korap/response/Result.java
index 0dabb24..32b3cfe 100644
--- a/src/main/java/de/ids_mannheim/korap/response/Result.java
+++ b/src/main/java/de/ids_mannheim/korap/response/Result.java
@@ -90,7 +90,7 @@
         this.serialQuery = query;
         this.startIndex = startIndex;
         this.itemsPerPage = (itemsPerPage > ITEMS_PER_PAGE_MAX
-                || itemsPerPage < 1) ? ITEMS_PER_PAGE : itemsPerPage;
+                || itemsPerPage < 0) ? ITEMS_PER_PAGE : itemsPerPage;
         this.context = context;
     };